Fungal extracellular carboxylic acids associated with ore mining: a wide perspective for the future

Organic acid produced through microbial activity can solubilize and precipitate metals in ores. Organic acids can change the pH or redox conditions and act as chelating agents. Fungi produce various chelating compounds and ligands as a byproduct of their metabolism. Organic acids including citric acid, oxalic acid, gluconic acid, tartaric acid, and pyruvic acid produced by different fungi can mobilize metals and are useful for bioleaching of oxide and silicate ores. Aspergillus and Penicillium genera are the most important filamentous fungi used for the extraction of metals from oxide ores. This chapter elucidates the role of organic acids produced by different fungal genera during the primary metabolism for the solubilization of metals of high economic interest.